[Zope3-dev] Re: Providing flexible adapters

[Shane Hathaway]

Steve Alexander wrote:
> Shane Hathaway wrote:
> 
>>
>> I agree, but I'm not sure that the normal case is an adapter.  
> 
> 
> Sounds like one to me... Here's an object. Give me an appropriate 
> IReference.
> 
> What could we possibly want to do under the hood that an adapter would 
> be incapable of, but a utility would be capable of?

Let's say we provide a ReferenceByPath adapter for all IFolder objects. 
  This is the normal case in Zope 2.  Then let's say we put a simple 
folder inside a placeful service.  Services can't be looked up by simple 
paths, so I guess we have to augment the contract of ReferenceByPath. 
Then let's say we put a simple folder inside a placeful user object (for 
storing preferences).  Users don't get looked up by simple paths either, 
so again we have to augment the contract of ReferenceByPath.  Then we 
want to refer to a simple folder accessible only via SOAP.  Wow.

In the end we have ReferenceByAnyPossiblePathOrURL, and we have followed 
the course of Zope 2.  We should have made it configurable.  We should 
have been able to make different kinds of references without modifying 
existing software.

We could use an URL protocol registry as Phillip suggested, but what 
happened to the very simple contract ReferenceByPath had?  What about 
ReferenceByOID?

You see, I don't think we can yet define all the axes that modify the 
choice of reference type.  Not even the object itself can adequately 
define how to make a reference to itself.  Utilities are meant to solve 
this class of problem.

Shane